2:01 AM
@EvanJenkins good to know. did i say they were? I don't really know about such things.

@Evan you should star the incriminating reply for posterity, I heard Jon loves that

@LoganM no I'm not. my officemate Vitaly is

@JonBeardsley I know Vitaly. Who are you working with then?
(btw I'm a physics grad at JHU, but the only math professors I know are Nitu and Jack)

oh! cool. I'm working with Jack
do you know Kevin Grizzard? he's a pretty good friend of mine.

@JonBeardsley Click the little arrow on my post.

2:05 AM
oh thanks! close one

@JonBeardsley Yeah I know him also.

oh cool. oh yeah! were you in Nitu's class? I was there for part of that.
do you have a big beard? I may know who you are.

Yeah I was there occasionally. If you were there you probably saw me. I'm the one with the obscene amount of hair on my face.

jon "no beard" beardsley

yeah, no beard for me

2:07 AM
Jon Beardless

and yeah, I saw you there, and in Jack's class I'm pretty sure. I'm the jerk that showed up to his class and hi-jacked him as soon he was done teaching you guys

Jon not-so-Beardsley

Oh yeah I remember you now. It's hard to recognize people just based on internet photos though.

yeah totally
and yeah. i'm Beardfree Beardsley
kind of like butterfree

2:10 AM
This seems like an opportune moment to make a shameless plug for my ridiculous Facial Hair Area51 proposal

during SXSW i saw a novelty band called The Beards
they have like 3 full length albums

This reminds me, I should update my gravatar.
This one is missing a beard.

that's a lot of music about beards
i like that really the only math that has been discussed in this room so far is type theory and algebraic geometry

come on
it was HOMOTOPY type theory
not completely irrelevant

well
yeah
but still, it makes my joke less funny
and besides, it was barely homotopy type theory

2:13 AM
and it was barely a joke

it was basically type theory with an infinitesimal arrow pointing at homotopy theory
that's true. more of an ironic observation

explain more jokes to me JB

do you know what the B is Benoit B. Mandelbrot stands for?
*in

Beardsley

It stands for Benoit B. Mandelbrot

2:16 AM
oh that's pretty funny

ZING

now explain it

hahah

yes I thought that was the point

i'm feeling cyberbullied
so Will, who are you anyway?

2:18 AM

no, i'm the room owner, I'm allowed to cyberbully

sorry master

lol
okay. time to go listen to Bossa Nova and do math
have a lovely evening all
Question
if an elliptic curve is given by some equation
y^2=x^3+Ax+B
or something
i mean......
isn't this an affine abelian variety?

2:25 AM
the origin is not contained in that set of solutions

You want the projective closure.

it's at infinity in that representation

You're taking y^2z = x^3 + Axz^2 + Bz^3
In projective 2-space

Yes, the additional point at infinity is the marked point.

2:25 AM
so, we can get an affine variety, but it's not a group

Right

super!

Actually, you can take any point as the marked point.

i see, but..... if it's not projectificated, it's not a group?
even if i take some other point as the identity

Right
Because there will be some pairs of points that add to the point at infinity.

2:27 AM
yes, right, kewl

The group operation is take two points, and find the third point that intersects the line they form.

yeah
okay, now, when i want to get the formal group law, i take the taylor expansion of the group structure at.... the marked point?
well.... "taylor expansion"

I'm not sure I agree with taking any point as the marked point
obviously youu can translate everything
but if you are doing chord-tangent you want to take a flex right

obviously
oh i see what you're saying, chord tangent, yeah

Oh, yes.

2:29 AM
genuinely.

With that definition of the group law.

what is a flex right
btw

a flex is a point at which the tangent intersects the curve with multiplicity at least 3

Inflection point

2:31 AM
Do I have a beard yet?

you want that for your point to be able to be an identity for the chord-tangent grop laaw

Maybe I need to log back in.

yes you do

you have a beard

everyone was too intimated by it to comment on it

2:31 AM
when i click on your name

@EvanJenkins Also make three comments in a row so your picture gets bigger

Ah, wunderbar.

like this

Candyman

a
d

2:32 AM
lol nice try!

we
Bigger

o
okay sorry i'll stop
no i wont
huge photo!

we have a winner

Sorry, tried to make a bunch of quick lines and the system wouldn't let me.
sdaer

Can
I
Just
Do
This?

2:33 AM
yes

Well that worked.

Yes
But I see no beard

except ur little picture is still your old one

I see the new one

And the big picture

2:33 AM
nah i'm seein that beard

I see the beard when I click

and that bow-tie. super choette
(sic)

Bow ties are cool

yeah, it's kind of all i wear now

Sorry, couldn't help myself

2:34 AM
except people keep saying to me "oh now you really look like a professor!"

Just a bow tie? How risqué.

but i never see professors wearing them

Well, I tried to convince my wife I didn't need to dress fancy to give a talk at a conference, citing Mike Hopkins as an example...

2:35 AM
hahah
i'd like to give a talk at a conference
i'd wear a bow-tie

Shorts and a T-shirt

you better believe it

But it's winter here, and it was Singapore then

that reads as if Singapore is a season

Singapore only has one season

2:36 AM
to e

It is.

Bang on the equator

i see

well it's not due just to that

Nice and warm all year around

2:36 AM
it's a lot of climate regulation from the ocean also

True

listen guys, please take this to the climatology.stackexchange chatroom

insert John Baez joke

Sorry, but I was talking about Mike Hopkins and his talk about E_\infty stuff

what if i made this room and just kept kicking everyone out, and just sat here talking to myself

2:37 AM
You are talking to yourself, we are all bots

it'd be like Arnav's room

what if that IS what I'm doing, I just don't know it
whoa, we all had the same thought

Re: Lem's Peace on Earth

That's because we're all you.

2:38 AM
yeah, Arnav's AG room
hahaha, excellent.

Hey, it's a great way to think out loud and keep a transcript

well, that's the only way i worked out that what i really wanted was a cogroup scheme

Good on you, Jon
Don't listen to those other nasty voices

indeed

Are you sure you didn't want a group coscheme?

2:39 AM
absolutely
though i like to think about cosheaves. by which i do not mean covariant functors satisfying descent

Codescent, you mean.

yeah sorry

Like Lawvere's quantity and quality

Also known as ascent!

that's not what i don't mean

2:40 AM
Intensive and extensive

yeah, totally. insensitive

Wow, now the system is being cranky and not letting me post comments quickly
as well
These are real mathematical things, you know.
All about topos-theoretic approaches to classical physics

no i mean a category fibered in grothendieck topologis

that is not a "real" thing

2:41 AM
No, no it's not

but it'd be cool if it were. also, sheaves of sheaves of sheaves of sheaves of....

A textbook example of toPoe's law: made-up topos-theoretic terminology is indistinguishable from the real thing.

so those are $\infty$-sheaves, right

don't pretend you wrote sheaves infinitely many times there

$\aleph_3$-sheaves
i did, the internet just couldn't handle it
i'm particular interested in $(\aleph_3,\aleph_2)$-categories

2:44 AM
I thought you were interested in large cardinals
those don't seem very large to me

i'm not actually

that's a relief

interested in anything
i don't know any big cardinals

Not even the Pope?

except the Reinhardt cardinal
which I'm pretty sure can't exist
or something
does mathematica solve systems of equations? it seems like it should really do that

2:46 AM
of course

because that's what i need to happen right now
but like, everything is symbolic, systems of equations in terms of just a whole bunch of constants

In the absence of AC we know of no reason why Reinhardt shouldn't exist.

oh that's right
and i'm not really down with AC anyway

is that a thing

2:47 AM
ref/Solve in the mathematica documentation gives examples

cool

I saw. But with homotopy type theory, you shouldn't need it.

holy shit, it WILL NOT let me post even remotely fast enought

Yes, was doing that to me too

can homotopy type theory fix my clogged kitchen sink?

2:48 AM
only if the clogging is simply connected

most likely not the case

Only if the clogging is nilpotent

Don't try to fix clogged sink with Coq.

hahhahaha
i already learned that the hard way.

Just use Require Import Sink

2:50 AM
my sister asked me what i do, and i was trying to explain to her the notion of contractibility, and she got really frustrated, because you just can't shrink anything that small
or at least, you'd need some kind of hydraulics or something

are we still talking about Coq?

ZING
and also: ew. that's my sister bro.

Sorry, Require Import Sink. (missing full stop)

Yeah, I didn't notice your mistake, my Coq is pretty rusty.
this is out of control. we're never going to get any grown up mathematicians in here

I noticed

2:53 AM
are you David P Roberts?

With all these puns, we'll only get groan-up mathematicians.

No, David Michael Roberts
:(
Evan

whoa. bigroupoids.
sweet.

I did say it was winter here

and bundle gerbes

2:55 AM
Will be doing a paper with Andrew Stacey making the fundamental bigroupoid into a Lie bigroupoid next

it's pretty funny to see the way people are in here, and then read their math papers, and how they're all serious and stuff

Bundle gerbes are the easy part

oh my

What?

just, that they're easy.
i know that they're stacks with some extra stuff, locally non-trivial, something something
i can never remember

2:56 AM
It's just a special sort of internal groupoid
OK: here's a crash course

yeah

are there nonabelian models for higher rank gerbes, like there are BU(n)s for higher rank vector bundles

Take a groupoid, say in schemes or spaces
(@Eric - yes, but trickier to get examples)

okay sure
taken

2:57 AM
yes

Call it X_1 => X_0, and take the map X_0 --> X_0/X_1

you can intro for now

@Eric ok - my emails on the nLab

alright
soooooo, objects mod morphisms, or something
like, FGL's mod isos

Yes - it's the space of orbits/pi_0 of the groupoid
Yes

2:59 AM
cool

Then the fibres of the functor X -> X_0/X_1 (I forgot to say I will call the groupoid X)
are transitive groupoids

aha
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